The 25-D1.16 monoclonal antibody reacts with the ovalbumin-derived peptide SIINFEKL bound to H-2Kb of MHC class I, but not with unbound H-2Kb, or H-2Kb bound with an irrelevant peptide. This antibody has proven to be very useful tracking the quantity and localization of these specific antigen-presenting cells (APC) in vivo.